1. Field of the Invention
The present invention relates to a formation method of a two-dimensional code by means of laser burning.
2. Description of the Prior Art
Generally, bar codes composed of printed stripes are used on packages of goods for merchandise control and accounting at a point of sales. Nevertheless, this bar code composed of stripes has a small amount of data to be recorded in comparison with an area to be used, and hence can be used only for control of article numbers of goods and the like.
For this reason, recently, a two-dimensional code that is formed by a matrix having a bright and dark dotted pattern has been used. Since this code can record 12 alphanumeric characters per 1 m square, the data amount per unit area is extremely large in comparison with that of the bar code. Therefore, this code has such advantages that the code can not only record plenty of data but also read the data from any direction, that is, the direction of 360xc2x0 with a reader. Furthermore, since this code not only has a function of recovering data even if a part of the code is damaged or stained, but also can secretly manage information by encrypting data, its application has been widespread.
When this two-dimensional code is generated, image data composed of a matrix having a bright and dark pattern is generated on a screen of a personal computer with using a graphic software. Conventionally, a two-dimensional code is formed on a marking surface with a method such as presswork, printing with a printer, and laser burning on the basis of a two-dimensional code generated from this image data.
A two-dimensional code 1, as shown in FIG. 23, records data by forming a plurality of cells 2 through dividing an inside of a square or a rectangle into a matrix, and arraying cells 2a, which are derived from cells 2 and are darkly filled, and bright cells 2b. For example, if 25 pieces of square cells 2 are formed by dividing a two-dimensional code 1, having an area of 1.2 mm square, into squares with 5 rows and 5 columns, each cell 2 is formed in the shape of a square each side of which is 240 xcexcm long.
When a cell 2a, which is darkly filled, is formed on a marking surface of metal, resin, or the like with heat of a laser beam by irradiating the laser beam on the marking surface, first, as shown in FIG. 24A, a cell 2 is linearly burnt with the laser beam sequentially from an upper portion to a lower portion with making the laser beam horizontally scan. Finally, as shown in FIG. 24B, the dark cell 2a is formed by burning the marking surface in a square totally.
In this system, since there is no regularity in radiation intervals of a laser, the laser beam may be irradiated out of a cell area, and hence, for example, as shown in FIG. 25, runover portion 3, caused by the laser beam deviating horizontally, and a blank portion 4 may arise in some cases. If a two-dimensional code 1 including such irregular cells 2a is formed on a marking surface as shown in FIG. 11, this causes a problem that the code may be read as erroneous data by a reader. In particular, in case of a minute two-dimensional code with only an area of 1 mm square, read errors increase, and hence this causes a problem that an advantage of the two-dimensional code which can record plenty of information is extinguished.
This is because it is not defined in a conventional system that vector data necessary for forming a cell exists only in a cell area. Thus, the conventional system does not recognize each of 25 cells, formed in a matrix with 5 rows and 5 columns, as a unit cell, but generates the two-dimensional code by sequentially combining line-drawing continuous data in bit-map data on the basis of image data. Therefore, a coordinate management system of recognizing a starting point and an end point of marking is not adopted, and hence this causes a problem that irregular cells are formed.
In addition, in a conventional formation method of a two-dimensional code with using a bit map data, there is such a problem that a two-dimensional code cannot be marked on a work whose area is small since the size of an area where the code is formed is predetermined. In particular, when a two-dimensional code is formed by laser burning, there is such a problem that, since a diameter of a laser beam is different from a diameter of a round dot processed every material to be processed, a high-precision two-dimensional code cannot be formed. In addition, the formation method of a two-dimensional code with using a bit map data has such a problem that it is difficult to store large volume of data due to necessity of large memory capacity. Furthermore, if two-dimensional codes are formed with using bit map data different every company, each laser marker dedicated to each company should be used.
The present invention can remove the above disadvantages. Thus, the present invention provides a formation method of a two-dimensional code that can save memory capacity for process data by replacing one cell with one bit, and can increase read precision by forming the two-dimensional code on a marking surface in high precision with accommodating positions of laser beam spots to process material through coordinate management. In particular, this method is effective for two-dimensional code configured by minute cells.
A formation method of a two-dimensional code according to a first aspect of the present invention is a method for forming the two-dimensional code, where unit cells each of which is in a dark or bright pattern are arranged in a matrix, on a marking surface by laser burning, the method comprising the steps of storing a bright or dark cell as an element of a two-dimensional array having a value of 0 or 1 after reading a bit map file, calculating a number of round dots contained in a cell from the size of one cell to be laser-marked and a processed diameter of a round dot formed by a laser beam according to material processed, obtaining a processed area from the two-dimensional array, which is stored and is configured by zeroes and ones, and the size of one cell, setting a plurality of cell frames at intervals of one cell width in the X and Y directions in a checked pattern with a center point of this processed area as a base, arranging the round dots inside corners of the cell frames so that the round dots may be inscribed in the corners and arranging the round dots at equal intervals between the round dots inscribed in the corners, storing in memory the coordinates of beam spots corresponding to centers of the respective round dots arranged in the processed area, and outputting this process data stored in the memory to a laser marker and performing laser-marking on the marking surface.
In addition, a formation method of a two-dimensional code according to a second aspect of the present invention is characterized in that, in the step of storing a bright or dark cell as an element of a two-dimensional array having a value of 0 or 1 after reading a bit map file, if a dark pattern or bright pattern in the bit map file is configured by rectangular cells each of which is configured by a plurality of bunching square cell elements, each cell is stored as an element of a two-dimensional array having a value of 0 or 1 after reading only one cell element in each cell.
Furthermore, a formation of a two-dimensional code according to a third aspect of the present invention is characterized in that, in the step of storing coordinates of beam spots, which correspond to centers of respective round dots arranged in a processed area, in memory, only beam spot coordinates of dark cells are stored in memory.